Blocking SDK2 worlds is needless. There are so many benefits to building worlds in SDK, such as performance and easy learning curve as well as simplicity of troubleshooting issues.
Udon is none of the above, and prefabbed automation tools do not solve this.
Many people do not even try to make worlds because of the daunting task of learning udon. And those that do mostly rely on the subpar graphing system or USharp automation prefabs which to the uneducated creator is the same as a black box for them, which hinders them from being able to troubleshoot or optimize it it effectively. Plus there's the lack of understanding on the importance of being frugal on udon operations.